1. Field of the Invention
The present invention relates to methods of cementing subterranean zones utilizing foamed or non-foamed cement compositions having improved rheology, fluid loss control and set retardation.
2. Description of the Prior Art
Foamed and non-foamed hydraulic cement compositions are often utilized in cementing subterranean zones penetrated by well bores. For example, foamed and non-foamed cement compositions are used in primary well cementing operations whereby strings of pipe such as casing and liners are cemented in well bores. In performing primary cementing, a cement composition is pumped into the annular space between the walls of a well bore and the exterior surfaces of a pipe string disposed therein. The cement composition is permitted to set in the annular space thereby forming an annular sheath of hardened substantially impermeable cement therein. The cement sheath physically supports and positions the pipe string in the well bore and bonds the exterior surfaces of the pipe string to the walls of the well bore whereby the undesirable migration of fluids between zones or formations penetrated by the well bore is prevented.
The foamed and non-foamed cement compositions utilized for cementing in subterranean zones penetrated by well bores must have good rheological properties, low fluid losses and sufficient set retardation at high temperatures. In addition, the cement compositions must have adequate thickening times and compressive strengths. Heretofore, carboxymethylhydroxyethylcellulose (CMHEC) has been used in foamed and non-foamed cement compositions to control fluid loss and provide set retardation to the cement compositions. While CMHEC has been used successfully as an additive in cement compositions used for cementing subterranean zones, there are continuing needs for improved cementing methods, cement compositions and cement additives for providing improved rheologies, viscosities, fluid loss control properties, thickening times and compressive strengths to cement compositions placed in subterranean zones.